A left ventricular assist system (LVAS) for chronic support of patients with left heart failure is being developed by us and is ready for clinical use in left heart failure for temporary support. The complete system (pump, energy system, batteries) will be ready for chronic human use in four years. Previous clinical experience with left ventricular assist devices (LVAD) has demonstrated right heart failure of unknown origin in a significant fraction of patients. Our principal research goal is to develop an LVAD for chronic use in patients with left heart failure. Therefore, we need knowledge now about the fate of right ventricular function following left ventricular (LV) unloading in diseased human hearts. This will prepare the way for selection of proper patients for chronic LVAS support as opposed to those who will require total hearts. We will study the effects of left ventricular unloading and assist on right ventricular function a) in patients in an operating room model which simulates the unloading effects of an LVAD; b) in patients with implanted clinical LVADs; and c) in an animal model. In the operating room model approximately 48 patients per year will be divided into groups on the basis of normal/abnormal 1) pulmonary blood pressure; 2) right ventricular myocardial circulation; and 3) interventricular septum. Approximately 10 studies per yer will be performed on patients with clinical LVADs implanted either post-surgery or in cardiogenic shock. The operating room protocol also will be duplicated for evaluation of the normal animal heart. Hypotheses will be tested concerning the effects of LV unloading on right ventricular function. Patients will be instrumented to determine RV function curves, ejection fraction, dp/dt, cardiac output, etc., under conditions of the left ventricle loaded at normal pressures and unloaded to systolic pressures around 20 mmHg. From this data the effects of cardiac disease on the pathophysiology of RV function after LV unloading will be developed and a physiologic description of the proper patients for successful chronic LVAD implantation constructed.